When an aircraft is flown during certain atmospheric conditions, ice can form and potentially accumulate on one or more of its exterior surfaces. Such ice formation and accumulation can result from, for example, impingement of atmospheric water droplets. The formation and accumulation of ice on some exterior surfaces can have adverse and/or deleterious effects on aircraft performance.
For example, following its formation on an exterior surface, ice can break loose and enter the aircraft engines, or collide with protruding surfaces such as antennas, wings, moveable control surfaces, or various structures on the ground. Ice accumulation on airfoil surfaces such as wings and empennages can also adversely affect airfoil aerodynamic performance. In addition, the weight of any accumulated ice may change the overall weight and/or center of gravity of the aircraft. Moreover, ice accumulation on moveable surfaces may interfere with the operation of the moveable surface. Consequently, many aircraft include an ice protection system that either prevents the formation of ice on aircraft surfaces or removes ice that forms on such surfaces.
The ice protection systems in many aircraft include one or more conduits, such as piccolo tubes, to deliver hot engine bleed air to the exterior surfaces that are to be anti-iced/de-iced. One or more upstream shut-off valves may also be mounted on the conduits to selectively supply and shut-off the flow of bleed air to the downstream surfaces. Many presently known ice protection systems may also include various control features such as, for example, pressure regulating valves, temperature feedback, valve opening rate controls, etc.
The presently known systems described above, while generally safe and reliable, do suffer certain drawbacks. For example, these systems can cause the flow of engine bleed air to exceed desired limits (e.g., engine over-bleeding). Hence, there is a need for an aircraft ice protection control system and method that mitigates engine over-bleed. The present invention addresses at least this need.